JPH02284381A - Lighting load controlling device - Google Patents

Abstract

PURPOSE:To prevent breakage or abnormal action of a control circuit of a lighting device by input an unstable dim signal to the control circuit by providing a delay element for delaying start of action of a control means till the dim signal generated by a dimming means gets stable. CONSTITUTION:After a voltage of an AC power source AC is converted at each lighting device 20 to a DC source, a high frequency converting circuit 1 consisting of a transistor, inverter, etc., is used for a stabilizer, and a lighting load 2 is lighted. A dim signal is supplied from a dim circuit 4 through dim signal lines l2, l3, and a lighting load 2 of a lighting device 20 is dimmed as desired corresponding to operation of a dim operation part such as a changeable resistor VR in a dim circuit 4. In this case, the control circuit 3 delays start of action till the dim signal of the dim circuit 4 gets stable. Breakage or abnormal action of a control means of the lighting device by input of an unstable dim signal to the control means can thus be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lighting load control device that dims and lights up a lighting load at high frequency.

[Prior Art] FIG. 12 is a circuit diagram of a conventional lighting load control device. The circuit configuration will be explained below. commercial alternating current power supply ac
is full-wave rectified by a diode bridge DB, smoothed by a capacitor C0, and converted into a DC power source E1. A series circuit of transistors Q 2 , Q − as main switching elements is connected in parallel to this DC power source E, and each transistor Q 2 . Q.

diodes DI and Dx are connected in antiparallel to each other. A load circuit is connected to both ends of the transistor Q2 via a coupling capacitor Cd for cutting off the DC component and a current transformer CT for feeding back the load current. The load circuit is composed of an LC resonance circuit including a lighting load 2 made of a discharge lamp, an inductor L1 for current limiting and resonance, a capacitor C2 for resonance, and a capacitor C1 for resonance and preheating current, and the load current becomes an oscillating current. This oscillating current flows through the primary winding of the current transformer CT. Therefore, 2 of the current transformer CT
A voltage whose polarity changes according to the oscillating current flowing through the load circuit is induced in the next winding, and this induced voltage is applied between the base and emitter of transistor Q2 via resistor R2 to switch transistor Q2. . The output signal of the control circuit 3 is supplied to the base of the transistor Q. In the control circuit 3, the voltage across the transistor Q is detected by resistors R, , R, and the transistor Q is turned on for a predetermined period of time after the voltage across the transistor Q falls.

This high frequency conversion circuit 1 includes a starting circuit for starting self-oscillation operation when the DC power source E1 is turned on. In this startup circuit, when the power is turned on, capacitor CI is charged via resistor R+, and when the charging voltage reaches the breakover voltage of 2-terminal thyristor Q, 2-terminal thyristor Q is turned on, and 2 terminals are connected to the base of transistor Q3.
A base current is caused to flow through the terminal thyristor Q to first turn on the transistor Q and start oscillation.

The operation of the circuit shown in FIG. 12 will be explained below.

When the power is turned on, the transistor Q is turned on by the startup circuit, and the voltage across it becomes "Low" level.

As a result, the control circuit 3 is triggered, and its output goes to the "'High"" level, and the on state of the transistor Q is maintained. When transistor Q is turned on, diode D0 becomes conductive and capacitor C6 is no longer charged, so the starting circuit stops. At this time, the secondary winding of the current transformer CT is wound with a polarity that applies a reverse bias voltage between the base and emitter of the transistor Q2, so the transistor Q2 maintains the OFF state. After a predetermined time set by the dimming circuit 4 has elapsed, the output of the control circuit 3 becomes "Low" level, and the transistor Q is turned off. When transistor Q is turned off, the collector current of transistor Q3 decreases, causing an inductor.

The residual inductance generates an opposite induced voltage, and the oscillating current flowing through the inductor L1 tends to flow in the same direction, so that the diode D becomes conductive.

Furthermore, the secondary winding of the current transformer CT generates a reverse induced voltage, so that the transistor Q2 is forward biased, and the transistor Q2 is turned on. Diode D
When the current in I becomes zero, current flows through transistor Q2 using the accumulated charge in capacitor Cd as a power source. At this time, the inductor.

The core of is magnetized linearly towards the saturation flux.

Eventually, when the core reaches saturation magnetic flux, the inductance sharply moves toward zero, resulting in transistor Q
The amount of time change in the collector current of No. 2 becomes infinite. When the collector current of the transistor Q2 reaches hfe times the base current, the transistor Q2 becomes unsaturated, the base current fed back from the current transformer CT decreases, and the transistor Q2 turns off. Even after the transistor Q2 is turned off, the oscillating current flowing through the inductor L1 tends to flow in the same direction, so the diode D becomes conductive and the load circuit,
A current flows through the path between the capacitor Cd and the DC power supply E.

When diode D2 conducts, the voltage across transistor Q3 becomes zero, so control circuit 3 is triggered,
The output of the control circuit 3 becomes "High" level, and the transistor Q is forward biased. After the oscillating current flowing through the diode D2 becomes zero, a current flows from the DC power source E1 through the path of the capacitor Cd, the load circuit, and the transistor Q. By repeating the above operations,
The oscillation operation of the inverter continues.

As the dimming signal supplied from the dimming circuit 4 to the control port R3, a signal having a constant frequency and a variable on-duty (ratio of on-time to one cycle) is used.

When the dimming variable resistor VR is changed between the minimum value and the maximum value, the on-duty of the dimming signal changes linearly in the range of 0% to 100%.

The control circuit 3 in the apparatus shown in FIG. 12 is supplied with a dimming signal having a variable on-duty as described above from the dimming circuit 4, and performs dimming control. This control circuit 3 is a general-purpose integrated circuit (for example, NEC μPD453
8) is equipped with a monostable multivibrator IC consisting of: This monostable multivibrator IC has a falling trigger input terminal B that changes from “High” level to “L” level.
After changing to the “ow” level, the output terminal Q remains “ow” for a certain period of time.
In this embodiment, the voltage across the transistor Q is detected by dividing the voltage across the transistor Q by a series circuit of resistors R:l and R4, and the output terminal q is at the "low" level. It is used as a trigger signal for the vibrator IC.The time when the output terminal Q of the monostable multivibrator ■C1 becomes “High” level (output terminal q
The time for which the signal becomes "Low" level) is determined by the time constant of the resistor R7 and the capacitor C1. The output terminal Q is connected to the base of a driving transistor Q4, and the output terminal q is connected to the base of a driving transistor Qs. The collector of transistor Q4 is connected to the positive pole of DC power supply E2, the emitter of transistor Q5 is connected to the negative pole of DC power supply E, and the emitter of transistor Q and the collector of transistor Q5 are connected to the base of transistor Q. There is. Therefore, monostable multivibrator C1 operates as a timer circuit for determining the on period of transistor Q. Monostable multivibrator ■Resistor R7 and capacitor C1 for setting the time constant of C1
The output of the operational amplifier (2) C2 is connected to the connection point of (2) via a diode (D) and a resistor (R6). Op amp I
C, is an impedance converter having an inverting input terminal connected to an output terminal, and outputs the voltage of the capacitor C2 applied to the non-inverting input terminal with a low impedance. A charge discharging resistor R7 is connected in parallel to the capacitor C1, and is charged by the output voltage of the operational amplifier IC. The operational amplifier IC3 is an impedance converter having an inverting input terminal connected to an output terminal, and outputs the voltage of the capacitor C6 applied to the non-inverting input terminal with a low impedance.

Capacitor C6 is charged by a constant current from current mirror circuit 8 including transistors Q, , Q, and is discharged when transistor Q connected in parallel to both ends is turned on. The constant current supplied from the current mirror circuit 8 to the capacitor C6 is the same as the current flowing from the DC power supply E2 to the resistor R@ via the transistor Qs.

A forward bias is applied to the base of the transistor Q@ by a voltage obtained by dividing the voltage of the DC power supply E2 by resistors R1° and R9. A transistor Q is connected to both ends of the resistor R9.

are connected in parallel, and the transistor Q is the dimmer circuit 4.
When turned on by the output of transistor Q6, the forward bias of transistor Q6 disappears and transistor Q is turned off. At this time, the capacitor C6 is charged by a constant current from the current mirror circuit 8, and its charging voltage V increases linearly. The waveform of the charging voltage vl of the capacitor C6 is a triangular wave whose frequency is constant and whose voltage rise period is equal to the on-time width of the dimming signal. Therefore, as the on-time width of the dimming signal becomes longer, the peak value of the charging voltage (2) of the capacitor C6 becomes higher. operational amplifier IC,
IC3, capacitor C6 and resistor R1 are capacitor C
The output voltage V2 is the peak DC voltage of the charging voltage (2) of the capacitor C6. Therefore, the output voltage V2 becomes a voltage that changes linearly in proportion to the on-duty of the dimming signal of the dimming circuit 4. In addition, the resistor R6 is a control resistor, which forms a current path in parallel with the resistor R9 according to the above output voltage (2), and increases the charging current of the capacitor C4 as the output voltage V2 increases, thereby creating a monostable multivibrator. This is to control the time constant of IC to a small value. As a result, as the on-duty of the dimming signal increases, the output voltage 2 increases, the time constant of the monostable multivibrator IC decreases, and the transistor Q
, the light output of the lighting load 2 decreases.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned conventional example, in the dimming circuit 4, the voltage is supplied from the AC power supply AC through the step-down transformer Tf, the diode bridge DB for full-wave rectification, and the current-limiting resistor R. , a smoothing electrolytic capacitor C is charged to obtain a DC power source E3. Therefore, after the power is turned on, the dimming signal output from the dimming circuit 4 becomes unstable until the DC power source E3 of the dimming circuit 4 is completely turned on. If such an unstable dimming signal is input to the control circuit 3 of the lighting device 20, the control circuit 3 may be destroyed or operate abnormally, and in some cases, it may cause the lighting device to malfunction. There was a problem.

The present invention has been made in view of these points, and its purpose is to prevent unstable dimming signals from being input to the control circuit of a lighting device, causing the control circuit to be destroyed or malfunctioning. An object of the present invention is to provide a lighting load control device that can prevent such problems from occurring.

[Means for Solving the Problems] FIG. 1 shows an example of a lighting load control device to which the present invention is applied. In this device, after converting the voltage of an AC power source AC into a DC power source in each lighting device 20, a high frequency conversion circuit 1 including a transistor inverter or the like is used as a ballast to light up a lighting load 2. Each lighting device 2
0 control circuit 3 via dimming signal lines 12.13,
A dimming signal is supplied from a dimming circuit 4. Then, the illumination load 2 of the lighting device 20 is arbitrarily dimmed in accordance with the operation of the dimming operation section (for example, variable resistor VR) in the dimming circuit 4. The control circuit 3 includes a delay element that delays the start of operation until the dimming signal of the dimming circuit 4 becomes stable.

[Operation] FIG. 2 is an explanatory diagram of the operation of the above device. Figure (a) shows the operation of the control circuit 3, and figure (b) shows the operation of the dimmer circuit 4. When the power is turned on at time 0, the dimmer circuit 4 switches on at time t1. After the dimming signal is stabilized, the control circuit 3 starts operating at time t2.

FIG. 3 is another explanatory diagram of the operation of the above device.

The figure (a) shows the operation of the control circuit 3, and the figure (b) shows the operation of the control circuit 3.
) shows the operation of the dimming circuit 4. When the power is turned on at time t0, the dimming signal of the dimming circuit 4 is stabilized at time t1, and output of the dimming signal is started at time t2. Thereafter, the control circuit 3 starts operating at time t.

FIG. 4 is another explanatory diagram of the operation of the above device.

The figure (a) shows the operation of the control circuit 3, and the figure (b) shows the operation of the control circuit 3.
) shows the rise of the DC power supply of the lighting device 20, and (c) of the same figure shows the rise of the DC power supply of the dimmer circuit 4. When the power is turned on at time t0, the time t
At time t2, the dimming signal is stabilized, and at time t2, the DC power source of the lighting device 20 is stabilized. After that, time t
, the operation of the control circuit 3 is started.

As described above, by delaying the start of the operation of the control circuit 3 until the dimming signal is stabilized, it is possible to prevent an unstable dimming signal from being input to the control circuit 3.

[Example 1] FIG. 5 is a circuit diagram of a first embodiment of the present invention.

In this embodiment, a transistor Q+s is connected in parallel to the transistor Q7 of the control circuit 3. When the transistor Q+s is on, both ends of the transistor Q are short-circuited, and the state is the same as if a stable dimming signal with an on-duty of 100% was input to the transistor Q. This transistor QCs is controlled by a signal from the dimming circuit 4.

The circuit configuration of the dimming circuit 4 used in this embodiment will be described below. The commercial AC power supply AC is stepped down by a step-down transformer Tf, full-wave rectified by a diode bridge DB, and charged into a smoothing capacitor C via a current-limiting resistor R. The voltage of capacitor C is regulated by a Zener diode ZD for voltage regulation, and is connected to a constant voltage DC power supply E.
, is obtained. The DC power supply E is divided by a variable resistor VR and applied as a reference voltage Vr to the non-inverting input terminal of the comparator ICs. A triangular wave oscillator 9 powered by a DC power source E generates a triangular wave voltage Vc, and applies it to the inverting input terminal of the comparator IC. The output terminal of the comparator I Ci is connected to the base of the transistor Q I 1 via a resistor R12. The emitter of transistor Q is connected to the negative pole of DC power supply E, and the collector is connected to the positive pole of DC power supply E through resistor R14, and the transistor Q + is connected through resistor R1.
Connected to the base of 2. The collector of the transistor Q1□ is connected to the positive electrode of the DC power source E, and the emitter is connected to the negative electrode of the DC power source E via the resistor FLs.

Then, a dimming signal Sn is obtained from both ends of the resistor R36. That is, transistor QIl and resistor R,,,R,.

This constitutes a common emitter type inverting amplifier circuit.
The transistor Q12 and the resistors R, s, R, . . . constitute a common collector (emitter follower) type impedance conversion circuit.

When the voltage Vc obtained from the triangular wave oscillator 9 is lower than the reference voltage Vr, the output terminal of the comparator IC is “
Since the transistor Q becomes "High" level, the transistor Q is turned on, its collector potential drops, and the dimming signal Sn becomes "Low" level.On the other hand, the voltage Vc obtained from the triangular wave oscillator 9 is lower than the reference voltage Vr. When the voltage becomes high, the output terminal of the comparator IC goes to the "Low" level, so the transistor Q turns off, its collector potential rises, and the dimming signal Sn goes to the "High" level. A dimming signal Sn consisting of a wave voltage is obtained.The reference voltage Vr can be set to an arbitrary voltage by operating the variable resistor VR, so the on-duty of the dimming signal Sn can be set to an arbitrary magnitude. This dimming signal Sn is supplied to the transistor Q of the control circuit 3, and the transistor Q
+s is off, as explained in the conventional example, the control voltage 2 of the control circuit 3 is made variable according to the on-duty of the dimming signal Sn, and the light output of the lighting load 2 is controlled. be.

By the way, the dimming signal Sn is not stable until the DC power supply E of the dimming circuit 4 starts up (time 0 to 1+ in FIG. 2(b)), and then the dimming signal Sn is stabilized. Until then, in order to turn on the transistor Q+s, the transistor Ql4 and the resistor R1? A stability detection circuit 12 is provided which includes R2 and a Zener diode ZD. When the power is turned on, the voltage across the capacitor C rises as shown by the curve in FIG. 2(b), but the voltage across the Zener diode ZD increases.

When the zener voltage of transistor Q + is not reached,
Since no base current flows through transistor Q +
4 remains off. At this time, the base current flows from the capacitor C to the transistor Q + s via the resistor R1°, so the transistor Q + s is turned on. Therefore, the state is the same as if transistor Q7 was turned on, and the on duty is 100%.
Similarly to the case where a stable dimming signal of is applied, the light output of the lighting load 2 becomes minimum.

Next, when the voltage of capacitor C reaches the Zener voltage of Zener diode ZD1, resistor R1? Since the base current flows through the transistor Q through the Zener diode ZD and the Zener diode ZD, the transistor Q + 4 is turned on. Therefore, the base current of the transistor Q + s is cut off, and the transistor Q + s is turned off.

At this time, since the dimming signal Sn of the dimming circuit 4 is stable, the control circuit 3 can stably control the light output of the lighting load 2 according to the dimming signal Sn of the dimming circuit 4. This is the result.

Furthermore, Figure 6 shows the Zener voltage V2D of the Zener diode ZD for voltage regulation and the Zener diode ZD for stability detection.
, shows the relationship between the Zener voltage VZDI. As shown in the figure, after the power is turned on at time t0, the voltage VC of the capacitor C reaches the Zener voltage VZD1 of the Zener diode ZD at time 2, and the transistor Q + 4 changes from OFF to ON. It is. After that, the voltage of capacitor C ■. is the zener voltage Vz of the zener diode ZD
D is reached and the voltage is regulated. Therefore, the Zener voltage VZDI of the Zener diode ZD for stability detection is set to a voltage value that is lower than the Zener voltage VZD of the Zener diode ZD for voltage regulation and allows the dimming circuit 4 to operate sufficiently stably. has been done.

[Example 2] FIG. 7 is a circuit diagram of a second embodiment of the present invention.

The dimming circuit 4 is provided with a stability detection circuit 12 composed of transistors Q, 4, resistors R, , R, and Zener diode ZD, as in the first embodiment, so that the dimming signal is unstable. By turning on the transistor QI3 for a certain period of time, the input to the transistor Q + 2 is cut off, so that the dimming signal Sn is not output. That is,
As shown in FIG. 3(b), the time is set. After turning on the power, the voltage of the DC power source E increases as shown by the curve in the figure, and the dimming signal stabilizes at time t1. After that, time t2
The transistor Q + + is turned off and outputs the dimming signal Sn.

On the other hand, the control circuit 3 of the lighting device is provided with a timer circuit 13, and as shown in FIG. 3(a), after the power is turned on at time E0, the transistor Q +
s is turned off, and reception of the dimming signal Sn begins. At this time, the relationship between times t and t2 is set so that h>h, and the unstable dimming signal Sn is never input to the control circuit 3 of the lighting device 20.

[Example 3] FIG. 8 is a circuit diagram of a third embodiment of the present invention.

In this embodiment, in Embodiment 2, the lighting device 20
The timer circuit 13 in the control circuit 3 is also used for starting compensation. After the power is turned on, the timer circuit 13 turns on the transistor Q I S r Q I for a certain period of time.
G is on. At this time, since the resistor R1 is short-circuited, the switching transistor Q.

The on-period of the lamp becomes shorter, the output of the high-frequency conversion circuit 1 decreases, and sufficient voltage is not supplied to both ends of the lighting load 2 consisting of a discharge lamp, so the discharge lamp does not light up and the preheating current flows through the filament of the discharge lamp. flows. After a certain period of time has elapsed, when the transistor Qls is turned off by the timer circuit 13, the on period of the switching transistor Q becomes longer, the output of the high frequency conversion circuit 1 increases, and the output from both ends of the lighting load 2 consisting of a discharge lamp increases. When the normal voltage is applied, the discharge lamp lights up. This makes it possible to perform starting compensation for the discharge lamp.
0 In normal discharge lamp lighting devices, a timer circuit as described above is often provided for the purpose of improving the life of the discharge lamp, and this timer circuit is used as a timer circuit for controlling the transistor Q + s. If used together, the present invention can be implemented at low cost.

[Example 41 FIG. 9 is a circuit diagram of a fourth embodiment of the present invention.

In this embodiment, the rise time of the DC power source E1 of the lighting device 20 is the same as the DC power source E of the dimmer circuit 4.

This is an example of a circuit assuming a case where the rise time is slower than the rise time of
The stability detection circuit 11 of the six lighting power supplies E1 which controls the transistor Q+s by the OR output of the stability detection circuit 12 of the signal power supply E.

This is similar to the stability detection circuit 12 (see Figure 5), and when the power supply voltage is stabilized, the output changes from "High" level to "'
For example, Fig. 4(c)
As shown in , after the power is turned on at time L0, at time t
When the signal power source E is stabilized at , the output of the stability detection circuit 12 changes from the "High" level to the "Los" level. Thereafter, as shown in FIG. 4(b), at time t
2, if the lighting power supply E is stabilized, the stability detection circuit 1
The output of No. 1 also changes from the "High" level to the "Lo-" level. As a result, the output of the OR circuit 10 becomes “Hi”
gh” level changes to “Low” level, as shown in Figure 4 (
As shown in a), the control circuit 3 starts operating at time t.

[Embodiment 5] FIG. 10 is a circuit diagram of a main part of a fifth embodiment of the present invention. In this embodiment, a three-terminal regulator 14 for voltage stabilization is provided in the power supply section of the dimming circuit 4. It is equipped with capacitors Ca and Cb on its input and output sides, respectively. In this case, the detection terminal C of the stability detection circuit 12 may be connected to one end a of the capacitor C&, or may be connected to one end of the capacitor cb. The same is true.

FIG. 11(a) is an operational waveform diagram when the detection terminal C of the stability detection circuit 12 is connected to one end a of the capacitor Ca. By turning on the power switch SW, capacitors Ca and C
The potentials V a and V b of b rise as shown in FIG. When the potential Va of the capacitor Ca reaches the Zener voltage VZD+ of the Zener diode ZDI, the transistor Q I 4 is turned on, the transistor Q 13 is turned off, and the dimming signal Sn is output. At this time,
The potential vb of the capacitor cb is already stable, and the dimming signal Sn is stable.

FIG. 11(b) is an operational waveform diagram when the detection terminal C of the stability detection circuit 12 is connected to one end of the capacitor cb. In this case, the zener voltage V2 of the zener diode ZD
Dl is set lower than in the case of FIG. 11(,), and the stability detection circuit 12 detects that the potential vb of the capacitor cb has risen sufficiently.

Any circuit example may be used as the stability detection circuit 12. In short, when the Zener diode ZD conducts,
It is sufficient that the dimming signal Sn of the dimming circuit 4 is stable.

[Effects of the Invention] As described above, in the present invention, in a high-frequency lighting device equipped with a means for controlling the light output of a lighting load, the operation of the control means is not started until the dimming signal generated by the dimming means is stabilized. This delay prevents unstable dimming signals from being input to the control means of the lighting device and destroying the control means.
This has the effect of preventing abnormal operation.

Note that if the timer circuit for delaying the start of operation of the control means is also used as a timer circuit for soft start or start compensation of the lighting device, the present invention can be carried out without causing a substantial increase in cost. This is particularly advantageous because it allows

[Brief explanation of drawings]

Fig. 1 is a circuit diagram for explaining the principle of the present invention, Figs. 2 to 4 are explanatory diagrams of the same operation as above, Fig. 5 is a circuit diagram of the first embodiment of the present invention, and Fig. 6 is the same as above. 7 is a circuit diagram of the second embodiment of the present invention, FIG. 8 is a circuit diagram of the third embodiment of the present invention, and FIG. 9 is a circuit diagram of the fourth embodiment of the present invention. 1
FIG. 0 is a circuit diagram of a main part of a fifth embodiment of the present invention, FIG. 11 is an explanatory diagram of the same operation as above, and FIG. 12 is a circuit diagram of a conventional example. E, , E, , E is a DC power supply, 1 is a high frequency conversion circuit, 2
is the lighting load, 3 is the control circuit, 4 is the dimming circuit, 11.12
2 is a stability detection circuit, and 20 is a lighting device.

Claims (2)

[Claims] (1) a DC power supply, a high-frequency conversion circuit that converts the DC voltage obtained from the DC power supply into a high-frequency voltage, and a lighting load to which the high-frequency voltage obtained from the high-frequency conversion circuit is applied;
A lighting load control device comprising: a control means for continuously varying the light output of the lighting load; and a light control means for providing the control means with a dimming signal for setting the light output of the lighting load. A lighting load control device comprising a delay element that delays the start of operation of a control means until a dimming signal becomes stable. (2) a first delay element that prohibits the output of the dimming signal until the dimming signal generated by the dimming means stabilizes after the power is turned on;
A second control unit prohibits the operation of the control means for a predetermined period of time after the power is turned on.
2. The lighting load control device according to claim 1, further comprising a delay element, wherein the delay time of the second delay element is set longer than the delay time of the first delay element.